This invention relates in general to testing apparatus and in particular to a new and useful device for testing blood samples which includes an attachment for connection to a measuring head and which comprises a chamber for the blood sample with a wall thereof which forms a membrane which engages over a closure membrane of the head.
The blood gas concentration is measured transcutane with known polarographic measurement heads placed on the skin of the patient. Reliable blood gas values can be obtained using transcutane measurements, where there is normal blood perfusion. However, in persons under shock, the perfusion is limited. In these cases the blood is to be measured directly. When applying the polarographic method only small blood amounts are sufficient from which the blood gas content can be determined.
Known measuring heads for measuring the blood gas content of small amounts of blood, for example two drops of blood, employ heated polarographic measuring heads, which up to now have been usable for the transcutane measurement of the perfusion efficiency. For this purpose they are screwed from below into the concentric opening of a body made, for example, from plexiglass. In this case the membrane surrounding the electrolyte fits to a well heat-conducting ring in a plexiglass body. This ring is provided with a conical bore forming a funnel shaped measuring trough. This trough is provided in its lower part with a bore which can be connected via an outlet with a suction pump. This bore can be closed with a cock. The blood amount entered into the trough stands on the membrane of the measuring head closing the trough opening at the bottom. The blood maintains the properties as in the core region of the blood vessels by the heat fed from the measuring head into the ring. The blood gas passes through the membrane of the measuring head into the electrolyte and is then determined. It is a disadvantage of this test system that the blood touches the membrane of the measuring head and that the head as well as the plexiglas body, has to be cleaned after each measurement. The sensitive membrane is easily damaged thereby, but at least it is worn off. Successive exchange and new calibration of the measuring head require considerable assembly work. (DE-OS No. 23 47 779).